New shine for the gold mine

Ford-Werke GmbH now uses a special material when partially renovating the waste water collection system during paint preparation in its paint shop at the Cologne site. The double-walled coating ensures a safe and above all testable sealing even in inaccessible parts of the line.

Todays cars are already "born" in traffic. Practically bumper to bumper – so that they can get one at this early stage – they push themselves through the production process of a highly modern factory. For example through the EC dipping bath (EC = electro coating) in the paint preparation at the Ford-Werke GmbH in Cologne Niehl.

In a three shift operation, day after day around the clock, nearly 2,000 body shells of the new Ford Fiesta and Ford Fusion receive a solid basis for a healthy paint job, and for a shiny running car life.

Quite different to the later real traffic jams on the streets of large German cities and motorways, the car parade in the Cologne Ford Works doesn't cause any headaches for the environment. Because here, in a modern automotive industry paint shop, not only is the air clear but every rivulet of water is also clear.

This is achieved using an environmental protection plan of the highest order, with which Ford has set a recognised mark in its branch of industry. Again and again the people of Cologne shine because of the use of innovative and trendsetting solutions.

So for example, in July of this year, a partial renovation of the waste water collection system in Area 2 of the paint shop: the paint preparation. Here, in Hall Y, situated in the immediate vicinity along the banks of the Rhine, the body shells are prephosphated and EC primed. They also receive a detailed seam sealing and even a highly resistant underseal protection.

EC dip coating: Everything is under way

The choicest parts of the, in total 28,500 square metre large paint preparation area, are without doubt each of the 400 m³ liquid containing EC baths. In them the previously phosphated body shells receive their cathodic dip paint coating.

In cathodic dip coating (CED), paint deposition occurs due to chemical conversions (coagulations) of the binding agent. They are triggered by an electrical flow from an outer electrode – the anode – across the conducting paint to the body – the cathode. Each body shell is completely dipped for about three minutes into the paint medium and then conveyed through the bath. During this coating process, currents of 1,000 to 2,000 amperes flow at a potential of up to 400 volts.

The cathodic dip coating process is ideal for automated coating. It is an extremely environmental friendly method because mainly water is used as a solvent. The paint yield is up to 98.5 percent. Which means that only 1.5 percent of the paint used is carried away. Cathodic dip coating gives a very even coating on metal surfaces and cavities with uniform layer thicknesses and top surface qualities.

After passing through the dipping bath, the coated body shells are conveyed to the EC drier, in which the applied coating layer is hardened (cured).

Electrophoretic dip painting gives the vehicles their main corrosion protection. The coatings applied in the following steps strengthen this protection even more; however they serve primarily for aesthetical and optical purposes.

Strict environmental regulations

"Here in Paint Preparation, because we can after successful use, incorporate our work material back into the process again practically to 100 percent, we operate as such extremely environmentally friendly", explains Daniel Pejkovski, planning engineer at Ford in Cologne in the "Plant Engineering & Layout paint shop" section. "This does not of course release us from the responsibility of also taking up additional extensive environmental protection measures and to monitor them regularly", he also states.

One of these measures, which is very significant, is easy to overlook when inspecting Area 2. Because when it is considered only spatially – takes place at a low level. But just this makes it so important.

We are talking about the waste water collection system in Hall Y. One detail that the lower water authority inspection officer from the technical inspection agency TÜV Rheinland is especially keeping a watchful eye over. No wonder, the subject of water pollution prevention applies right here, being only a few metres away from the Rhine river and in a ground water sensitive region, it plays an especially important role.

Because – as already mentioned – in EC dip coating the liquid can be reused practically without limit, there is almost no waste water from this area in the usual industrial sense. This is how the collection system in the paint preparation serves foremost the prevention and the uptake of comparatively less quantities of drop down. These accumulate while transporting the body shells between the cathodic dip painting baths and the EC drier.

The goldmine: Where everything comes together

The collection system consists of several, almost 200 metre long troughs, which run along and between the dipping baths, and the Hall Y liquid containers. About 50 centimetres wide, they are of varying depth along the course of a light gradient of between 50 and 90 centimetres.

These troughs are interrupted by three pits that are equipped with pumps, which serve as collection baths if there is suddenly a larger amount of liquid. The entire capacity of these intermediate pits and the troughs is alone enough to be able to reliably catch the complete contents of a cathodic dip bath (CED). "However, in the entire 25 year history of our section there has never been an accident that could be considered as being even slightly close to this order of magnitude", ensures Daniel Pejkovski.

And, for safety at Ford there is also another quite special "gem" – the so-call gold mine. This is another waste water pit directly in the vicinity of the dipping baths and the body shells dripping-off table's transport route to the drier section.

The concrete pit got its unusual name decades ago due to it being equipped with a 30 m³ liquid holding stainless steel tank. Planning engineer Daniel Pejkovski said: "This part was at the time so shockingly expensive, that the name gold pit came about."

Delivery pipes run into the gold pit, which incorporated into the troughs, follow their course up to the connection points at the liquid tanks and the EC dip coating baths. If necessary – for example during rotary-based cleaning work – liquids can be guided along the pipes from tanks and baths directly into the gold pit's stainless steel tank. Additionally, it can take up liquids that may be brought by the troughs. Thus the gold pit is the catchment systems main collection bath.

This summer, after decades of operation, the gold pit required an extensive renovation – above all regarding the stainless steel tank's seal tightness.

In view of the tightened environmental protection requirements, it was also necessary during the renovation to achieve permanent seal tightness monitoring and be capable of being tested.

Initially this seemed to be an insolvable task. Because the tank built into the concrete shell of the gold pit, could only be optically tested from two sides: At the front and to a limited extent from above. Four of the sides relevant to the legally required monitoring were however virtually inaccessible: Left and right sides, rear wall and floor of the stainless steel tank. What should be done?

Double-walled, monitorable coating

For project manager Daniel Pejkovski there was only one way out of this precarious situation; to go to the German specialists for coating technology, plant renovation and construction, GBT Bücolit GmbH in Marl, North Rhine-Westphalia.

However, almost 25 years ago the coating and renovation experts had already lined the EC dip baths for the Ford factory in Cologne, a trusted partner. And in the follow on period successfully renovated this and many other plant parts according to schedule.

Indeed, these projects these projects had taken place in the Ford paint shop, long before his time as planning engineer had begun, but Daniel Pejkovski knew about a very special material that GBT uses for protection-coating heavily exposed, extremely sensitive surfaces: Bücocontrol.

This being a highly solvent resistant laminate coating based on vinyl or polyester resin and using glass fibre matting for reinforcement. "but that in itself is nothing exceptional", explains GBT manager and founder Martin Konzack. "What is special about Bücocontrol is that by incorporating a 3D textile any desirable distance can be achieved between the first and second coating layers. This creates an extremely flexible formable double-walled coating. Of particular interest is that the intermediate space created between the double-walled coating can be used for a hundred percent leakage monitoring."

To achieve this, the space in between is subjected to a defined air pressure using approved leak indicating devices. Should a leak occur then this pressure breaks down and the fault is then reported by the indicating devices.

The advantage of Bücocontrol compared to similar materials is that it can be pressurised. Whereas conventionally a vacuum is applied. "In the vacuum method", explains Martin Konzack from GBT-Bücolit, "it is highly likely that the contents of the tank would be pulled through the leak into the spacing between the coating layers. This just makes the problem worse. If there is a positive pressure this cannot occur because the applied pressure acts like a cork closing off the tank's contents."

Nevertheless, Bücocontrol, as the user requires, is also suitable for the vacuum method. Of course there is a general building inspectorate approval from the German institute for building technology (DIBt) for Bücocontrol, which also complies with the German water resources management act (WHG) and the substances hazardous to water (VAwS) regulations.

The material can be applied to steel as well as concrete and is highly resistant to aggressive chemicals. Its laminated construction allows it to be formed without difficulty to fit complex geometrical shapes. This makes it ideal as a double-walled lining for container, container floors, vats and pump sumps.

Which is exactly what Ford in Cologne were looking for to achieve a perfect renovation of the difficult to access 'gold pit', the additional pump sumps and the drain troughs in the paint shop.

All ready

GBT's specialists only required twelve days to complete the full renovation project – three less than specified by Ford.

However, Daniel Pejkovski, responsible at Ford, was not really surprised: "I knew from previous projects that the GBT team are extremely fast-acting. This being one reason, another is the innovative material development; this is why GBT is the first choice general contractor for further projects here in the paint shop."